Embodiments of the present invention relate to imaging, and more particularly to predictive autofocusing of an imaging device.
High-density solid-state detector technology, coupled with affordable, terabyte and higher scale data storage, has greatly facilitated digital recording of industrial and medical images. In the biological and medical realm, digital microscopy has been used for such applications as high throughput screening, archiving, telemedicine, and rapid information retrieval. Digital microscopy is often advantageous over conventional light microscopy since hands-free operation of the microscope can increase throughput and reduce time and cost of operation. However, fully automated microscopy eliminates the optimization brought by a skilled human operator, such as the task of keeping the sample in focus during observation. Although microscopy samples are often relatively thin, on the order of a few micrometers, the high power objective lenses typically used for imaging have a depth of field that is even smaller. Accordingly, it is difficult to maintain the sample at the optimal focal position due to variations in the sample.
Conventional imaging devices perform autofocusing by directing a laser beam at the sample, measuring a reflection of the laser beam off the sample to provide a single reference point, and using a feedback loop to adjust the focal distance. Although this approach may provide rapid autofocusing, the single reference point may lack sufficient information for accurate autofocusing.
Conventional imaging devices also perform autofocusing by obtaining multiple images of a stationary sample at multiple focal distances, determining an optimal focal distance for each of the images and using a feedback loop to adjust the focal distance. Although this approach may provide more accurate autofocusing than the use of a laser beam, acquisition of the numerous images often creates time delays that prevent rapid autofocusing.
Therefore, there is a need for an imaging device that performs accurate rapid autofocusing in real-time image acquisition applications.